Technical Field
The present invention relates to an apparatus for controlling a wiper motor for a wiper system, and more particularly, to an apparatus for controlling a wiper motor for a wiper system for preventing a transient voltage generated when a wiper motor, to which high-voltage power is applied, is compulsorily stopped after a multifunctional switch is turned off.
Background Art
In general, a wiper system for removing foreign substances and wipe snow or rainwater on surfaces of windshield glass or rear window glass is installed in a vehicle.
The wiper system of the vehicle, which is an apparatus for wiping glass through an operation of a wiper blade rotated by a wiper motor, serves to secure a view of a driver.
The wiper system for a vehicle generally has a structure in which a rotation movement generated in the wiper motor is transmitted to pivot mechanism and a wiper arm through a wiper link, the wiper arm horizontally reciprocates, and the wiper blade moves to wipe glass.
Recently, the wiper system is controlled by an operation of the wiper motor by a body control module (BCM) within a vehicle and the like.
In the meantime, an operation mode of the wiper system includes a low mode and a high mode, and the total number of terminals of the wiper motor controlled by the BCM is four.
Among the terminals of the wiper motor, an E-terminal is a ground (−) terminal, a P-terminal is a parking control terminal, an H-terminal is a high mode terminal, and an L-terminal is a low mode terminal.
Further, the wiper motor includes a cam plate, and internal contact points formed by the P-terminal and the E-terminal connected and disconnected by the cam plate.
The cam plate is installed so as to be integrally rotated with a worm gear (worm wheel) rotated by receiving rotational force of a motor within the wiper motor, and the P-terminal of the internal contact point is connected to the E-terminal one time according to a position of the wiper blade during one rotation.
In the wiper system, the wiper blade reciprocates one time by the driving of the wiper motor during one rotation of the cam plate to wipe the glass, and in this case, the P-terminal and the E-terminal of the wiper motor are connected by the cam plate, so that the wiper blade is stopped at a predetermined parking position.
However, the wiper system in the related art may generate a transient voltage when the wiper blade enters a stop position (parking position) after a user turns off the multifunctional switch.
FIG. 1 is a diagram illustrating an example of an operation form of a cam plate for a wiper motor in the related art, FIG. 2 is a circuit diagram for a control of the wiper motor of a wiper system in the related art, FIG. 3 is a flowchart illustrating a process of controlling an operation of the wiper motor in the related art, and FIG. 4 is a graph illustrating a problem of the control of the wiper motor in the related art.
Referring to FIG. 1, the wiper motor includes a cam plate 2 installed so as to be integrally rotated with a gear part 1 (worm gear) integrally rotated with a shaft of a motor, and internal contact points formed by a P-terminal 3 and an E-terminal 4 connected and disconnected by the cam plate 2.
The cam plate 2 rotationally moves together with the worm gear 1 during an operation of the wiper motor, and disconnects the P-terminal 3 and the E-terminal 4 of the wiper motor in a normal operation section, in which a wiper blade reciprocates for one rotation, and is in contact with the P-terminal 3 and the E-terminal 4 of the wiper motor at the same time to connect the P-terminal 3 and the E-terminal 4 in a stop section, in which the movement of the wiper blade is stopped for one rotation.
Referring to FIGS. 2 and 3, in the apparatus for controlling the wiper motor in the related art, when a user turns off a multifunctional switch (not illustrated), and then the cam plate 2 is in contact with the P-terminal 3 and the E-terminal 4 of the wiper motor at the same time, and the P-terminal 3 and the E-terminal 4 are connected, 0 V is applied to the P-terminal 3, and when the BCM 6 recognizes 0 V of the P-terminal 3, the BCM contacts a low relay 8 to an off terminal 8a connected to the ground to compulsorily stops the motor.
That is, in the apparatus for controlling the wiper motor in the related art, when the BCM 6 applies (outputs) a motor stop signal after the user turns off the multifunctional switch, the low relay 8 within a junction box of an engine room is in contact with the ground (off terminal) and electromotive force applied to the wiper motor is momentarily decreased to 0 V, and the wiper motor is compulsorily stopped.
In this case, the wiper motor is compulsorily stopped in a state where high-voltage power is applied, so that a transient voltage is generated (see FIG. 4), that is, the electromotive force applied to the wiper motor sharply enters 0 V when the motor stops, so that a transient voltage is generated, and the transient voltage damages an element connected with the same power supply terminal and causes a jerking (shaking) phenomenon when the wiper blade enters the stop position (parking position).
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.